msm: ipa3: Enable HOLB on MHIP RMNET before stopping USB

Enable HOLB to drop packets on MHIP RMNET CONS before
stopping USB PROD and disabling it back during USB PROD
start channel.

Change-Id: I521826cea9dcb0c9ca884e9e075ea62bca0f16b3
Acked-by: Suhas Mallesh <smallesh@qti.qualcomm.com>
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>